In recent years, the role of chemical mediators in asthma and other allergic diseases has been quickly elucidated. In addition to histamine, PAF, leukotrienes, thromboxane A.sub.2, etc. have become known. It has been shown that leukotrienes are biosynthesized by the action of 5-ipoxygenase from arachidonic acid, and thromboxane A.sub.2 is biosynthesized by thromboxane synthase after the catabolism with cyclooxygenase from arachidonic acid. Further, leukotrienes and thromboxane A.sub.2 have both been found to be important chemical mediators in allergic reactions causing various diseases such as asthma, psoriasis, enteritis, nephritis, ulcers, and ischemia. Therefore, if it were possible to inhibit the biosynthesis of both chemical mediators, a greater effect could be obtained in treating or alleviating the above diseases when compared with the inhibition of single mediator.
Recently, as compounds for inhibiting the biosynthesis of such two mediators, benzothiazole derivatives (Japanese Unexamined Patent Publication (Kokai) No. 5-178855), quinone derivatives (Japanese Unexamined Patent Publication (Kokai) No. 5-78321), imidazolylphenol derivatives (Japanese Unexamined Patent Publication (Kokai) No. 6-9571), and N-hydroxyurea derivatives (WO96/23772) have become known.